As the number of user terminals (User Equipment, UE) constantly increases, micro base stations are increasingly deployed in a network of an operator, so as to distribute the data traffic of a macro base station and lower the processing pressure of the macro base station. This kind of network with mixed deployment of a macro base station and micro base stations is also referred to as a heterogeneous network (HetNet).
Referring to FIG. 1, FIG. 1 is a schematic diagram of an existing heterogeneous network. In the heterogeneous network shown in FIG. 1, when a UE served by a macro base station is outside a downlink coverage area of a micro base station and is located at an edge of the downlink coverage area of the micro base station, an uplink signal from the UE served by the macro base station to the macro base station causes uplink interference to the micro base station, and in this case, the UE served by the macro base station may be referred to as an interference source of the micro base station. To identify an interference source of a micro base station, some methods are currently put forward in the industry. These methods include: detecting, by a micro base station, an uplink sounding reference signal (SRS), an uplink preamble, or an uplink demodulation reference signal (DMRS) of a UE served by a macro base station, and feeding the uplink sounding reference signal, the uplink preamble, or the uplink demodulation reference signal back to the macro base station; and completing, by the macro base station, identification of an interference source.
In actual application, a base station can only successfully detect an uplink signal when the uplink signal of a UE served by the base station reaches the base station in an interval from a starting point of a receive window of the base station to ending of a cyclic prefix (CP). To meet this requirement, the base station generally allocates timing advanced (TA) to the UE, so as to enable the UE to learn how long the uplink signal should be sent ahead of time, so that the uplink signal of the UE may reach the base station in the interval from the starting point of the receive window of the base station to the ending of the cyclic prefix (CP).
In a heterogeneous network, when a UE served by a macro base station is outside a downlink coverage area of a micro base station, but is located at an edge of the downlink coverage area of the micro base station, the UE served by the macro base station sends an uplink signal by using TA allocated by the macro base station, because the UE is far from the macro base station, the TA allocated by the macro base station to the UE is generally large; because the UE is close to the micro base station, the uplink signal sent by the UE may reach the micro base station before a starting point of a receive window of the micro base station, so that the micro base station cannot detect the uplink signal sent by the UE.